linux-kernel - Re: [PATCH 3/7] mm/gup: remove vmas parameter from get_user_pages

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Date:   Sat, 15 Apr 2023 09:25:51 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     Lorenzo Stoakes <lstoakes@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/7] mm/gup: remove vmas parameter from
 get_user_pages_remote()

On 2023/04/15 8:27, Lorenzo Stoakes wrote:
> diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
> index f5bcb0dc6267..74d8d4007dec 100644
> --- a/arch/arm64/kernel/mte.c
> +++ b/arch/arm64/kernel/mte.c
> @@ -437,8 +437,9 @@ static int __access_remote_tags(struct mm_struct *mm, unsigned long addr,
>  		struct page *page = NULL;
>  
>  		ret = get_user_pages_remote(mm, addr, 1, gup_flags, &page,
> -					    &vma, NULL);
> -		if (ret <= 0)
> +					    NULL);
> +		vma = vma_lookup(mm, addr);
> +		if (ret <= 0 || !vma)
>  			break;

This conversion looks wrong. When get_user_pages_remote(&page) returned > 0,
put_page(page) is needed even if vma_lookup() returned NULL, isn't it?